# RE: Calculation of half life

From: Pavel Belo <nonmem>
Date: Wed, 30 Mar 2016 13:34:57 -0400 (EDT)

You can add formulas to NONMEM code.  All individual noncompartm=
ental
parameters can be calculated within NONMEM.  An example of the NONMEM=

code is below.  tH

DADT(6) = A(8) ;calculates AUC if A is concentration
DATD(8) = [put here the right part of the differential equation wh=
ich
calculates concentration]

CONC=A(8)
AUC =A(6)
AUCT=A(12)

IF (CONC.GT.1E-20) THEN

LAM=-([put here the right part of the
differential equation which calculates concentration]/CONC

ELSE

LAM=666666666

ENDIF

IF (AUC.GT.1E-20) THEN

MRT=AUCT/AUC

ELSE

MRT=666666666;

ENDIF

IF (AUC.GT.1E-20.AND.MWT.GE.0.000001) THEN

CL =DKG*BIO/(AUC*MWT)

ELSE

CL =666666666

ENDIF

VSS=MRT*CL

IF (DABS(LAM).GT.1E-20) THEN

IHL=0.693147/LAM

ELSE

LAM=666666666

IHL=666666666

ENDIF

IF (DABS(LAM).GT.1E-10.AND.AUC.GE.1E-10) THEN

VZ =DKG*BIO/(LAM*AUC*MWT)

ELSE

VZ =666666666

ENDIF

AQ=1;

BQ=K23+K32+KED;

CQ=K32*KED;

DQ=BQ**2-4*AQ*CQ;

BET2=666666666

IF (DQ.GE.0) BET2=(-BQ+SQRT(DQ))/(2*AQ);

BHLK= KED*(K32/(K32 + K23))

IF (BET2.LT.-1E-10) THEN

BHL=-LOG(2)/BET2;

ELSE

BHL=666666666

ENDIF

IF (DABS(A1).GE.1E10) A1=6666666

IF (DABS(A2).GE.1E10) A2=6666666

IF (DABS(A3).GE.1E10) A3=6666666

IF (DABS(A4).GE.1E10) A4=6666666

IF (DABS(A5).GE.1E10) A5=6666666

IF (DABS(IHL).GE.1E10) IHL=6666666

IF (DABS(MRT).GE.1E10) MRT=6666666

IF (DABS(CL).GE.1E10) CL=6666666

IF (DABS(VSS).GE.1E10) VSS=6666666

IF (DABS(LAM).GE.1E10) LAM=6666666

IF (DABS(VZ).GE.1E10) VZ=6666666

IF (DABS(BHL).GE.1E10) BHL=6666666

IF (DABS(BHLK).GE.1E10) BHLK=6666666

On Wed, Mar 30, 2016 at 11:40 AM, Santosh wrote:

Dear all,
I am looking for ways to calculate t[1/2,lamda,z] the elimination phase
half life, using  a 3-compartment model. ADVAN 12 and TRANS6 seems to =
be
a way. However, I am using the intercompartment clearance and volumes
based parameterization, e.g. Q3,V3 etc..

half.life = log(2)/gamma

Could anyone please share NONMEM code to compute the half-life based on
gamma?